Caleb Carr's latest is The Italian Secretary: A Further Adventure of Sherlock Holmes (Carroll & Graf). PW reached Carr, who's best known for his Alienist novels (The Alienist and The Angel of Darkness), at his office at Bard College, where he teaches military and diplomatic studies.

PW: Why do so many popular authors try their hand at a Holmes story?

CC: I think my interest in Holmes is probably like a lot of authors'. There are authors for whom the Holmes stories are part of the beginning of their decision to become writers, especially writers who aspire to popular fiction that has a bit more to it. Conan Doyle remains, along with a few others, the model of how to do that—how to write popular fiction that has a transcendent importance within not just literature but within the use that literature has in society. There's a reason why Sherlock Holmes is the best-known character in the world. It has to do with what reading is all about. I think that authors who aspire to not just express themselves—to not just write memoir fiction, to not just do all the nonsense that's so popular in our own era—feel they have to come to terms with Holmes at some point.

PW: In most thrillers and many mysteries, the plot concerns a small crime that later is related to a grand conspiracy. Yet in The Italian Secretary the plot runs in the opposite direction—what at first seems a grand conspiracy turns out to be a small, sordid crime. Why?

CC: Totally deliberate. There is a tendency among people to seek larger conspiracies. And yet in reality most crime is very intimate. I don't like most thrillers for that reason. In reality, serial killers tend to be very intimate. Their work is very personal in its rules and rituals. It's a funny thing, how many of the best mystery writers have had some personal experience of murder. And if you have had that, if you've, as in my case, grown up with a murderer [Carr's father, Lucien] or, in the case of somebody like Anne Perry, been a murderer, there's a clear recognition that murder is not be played with in that way. That's why in my own work, even when murder begins to appear to be part of a great conspiracy, it always turns out that there's some terribly personal and, generally, tragic dimension to it.

PW: I was surprised to seeThe Italian Secretary carries an afterword by John Lellenberg [the representative of the Conan Doyle estate in the U.S] in which he pleads that you write a novel featuring both Holmes and Laszlo Kreizler [hero of the Alienist novels].

CC: I was startled to see that, too. A lot of people had asked me, Did you ever think about a story with Holmes and Kreizler together? and the idea seemed so presumptuous that I dismissed it out of hand. But when someone like John says, That would be a great idea, I think to myself, Could I actually do it?

PW: Still, I suspect that most everyone who reads that afterword is going to say, Of course! Carr should write this.

CC: That's flattering, but as much as I hope The Italian Secretary is a good and faithful Holmes story, it is still not Arthur Conan Doyle. There is still a sense within me that it's not really Sherlock Holmes. Only Conan Doyle can write real Sherlock Holmes.

PW: You say it's not "real" Sherlock Holmes, but you understand that Holmes now resides within the psyche of humanity.

CC: I'm doing another Alienist book now, and one of the reasons is that I went through a long period when I thought, I can't. Those books drained me physically and psychologically and I didn't know if I could do another. But a friend at Random House told me how consistently high the sales of the two Alienist books have been, and how consistently large the response. That shocked me. And so I think I have some personal understanding of how characters and books, mostly characters, become the possession of a wider world than just yours.